convert string to hexadecimal

kpachopoulos · 12-11-2007, 02:36 AM

Hi,
i am using the following code, in order to convert a char array (or string) to its hexadecimal representation:

Code:

	byte hexval=0x00;
	cout << "sscanf: ";
	char car2[2];
	car2[0]='1';
	car2[1]='9';
	sscanf( car2, "0x%02X", &hexval );	
	printf("0x%02X", hexval);

However, i get back the "0x00" value. With other "experiments" i didn't also manage to get the "0x13" back.

Ideas?
Thanks

Looking_Lost · 12-11-2007, 03:57 AM

I assume the number in the string will be base ten as you want 19=0x13

Code:

	unsigned char hexval=0x00;
	cout << "sscanf: ";
	char car2[3];
	car2[0]='1';
	car2[1]='9';
	car2[2]='\0';
	sscanf( car2, "%2d", &hexval );	
	printf("0x%2X", hexval);

Hivemind · 12-11-2007, 05:45 AM

There are some things in the C++ standard library you could use to easily solve this problem. Here's an example:

Code:

#include <iomanip>
#include <iostream>
#include <sstream>

using namespace std;

void print_in_hex_form(const string& s)
{
   istringstream iss(s);
   int n;

   if (!(iss >> n))
   {
      cout << "Not a number!" << endl;
   }
   else
   {
      cout << hex << "0x" << n << endl;
   }
}

int main()
{
   print_in_hex_form("1337");
   print_in_hex_form("15");
   print_in_hex_form("0");
}

When run it prints:

Code:

$ ./runme.exe
0x539
0xf
0x0

lali.p · 12-11-2007, 06:23 AM

wow!!! thats why everbody loves standard library !!!!
cheers + beers = first love

Regards lali.p